A volcano is a geological structure where a rupture in the crust allows lava, ash, and gases to escape from a magma chamber below the surface. Determining the world’s tallest volcano is complicated because “tallest” can be measured in two distinct ways: height above sea level, or total height from the base to the summit. Using the standard measurement of elevation above sea level, the title belongs to Ojos del Salado, a massive volcanic complex in the Andes Mountains. However, a different perspective of measurement reveals an even taller structure.
The World’s Highest Volcano Above Sea Level
Nevado Ojos del Salado, located on the border between Chile and Argentina, is officially recognized as the world’s highest volcano above sea level. Its summit reaches an elevation of 6,893 meters (22,615 feet) above mean sea level. The mountain is an immense complex volcano, characterized by multiple overlapping lava domes and volcanic craters.
Ojos del Salado is classified as a stratovolcano, built up over time by layers of hardened lava, tephra, and volcanic ash. It is considered active but currently dormant, with its last confirmed eruption occurring approximately 1,000 to 1,500 years ago. Evidence of its activity includes active fumaroles near the summit, which release gases and steam.
The volcano’s location near the arid Atacama Desert results in dry conditions, preventing the formation of large, permanent glaciers. Despite the dry climate, a permanent crater lake exists on the eastern side of the mountain at an elevation of about 6,390 meters (20,960 feet). This feature holds the distinction of being the highest lake of any kind in the world.
Defining Height: Base-to-Peak Measurement
While elevation above sea level is the common metric, geologists often use an alternative method: measuring from the mountain’s true base to its peak. This base-to-peak measurement considers the entire vertical mass of the structure, including the portion submerged beneath the ocean floor. When measured this way, the title of the tallest volcano shifts from the Andes to the Pacific Ocean.
Mauna Kea, a massive shield volcano on the island of Hawaiʻi, holds the record for the tallest mountain on Earth by this definition. Its peak rises 4,207 meters (13,803 feet) above sea level, but the vast majority of its bulk lies beneath the waves. From its base, resting deep within the Hawaiian Trough, the volcano measures approximately 10,205 meters (33,480 feet) in total vertical height.
This colossal measurement makes Mauna Kea taller from base to peak than Mount Everest, which is indisputably the highest mountain above sea level. Mauna Kea is classified as a shield volcano, characterized by broad, gently sloping sides formed by the eruption of highly fluid, low-viscosity lava flows. The entire structure was created as the Pacific tectonic plate moved over a fixed deep-mantle plume, known as the Hawaiian hotspot.
Contextualizing Earth’s Tallest Peaks
The two record-holding volcanoes represent different geological mechanisms that create immense vertical relief. Ojos del Salado is part of the Andes mountain range, formed by plate subduction, a process that crumples the crust and builds steep, conical stratovolcanoes. This type of plate boundary setting is responsible for many of the planet’s highest continental peaks.
In contrast, Mauna Kea formed over a mid-plate volcanic hotspot, which continuously fed magma to the seafloor, steadily building an enormous, wide-based mountain. Another notable massive volcano is Mount Kilimanjaro in Tanzania, Africa’s highest peak at 5,895 meters (19,341 feet). Kilimanjaro is considered the world’s largest free-standing mountain, meaning it is not part of a mountain range.
Chimborazo, an inactive stratovolcano in Ecuador, is another high volcanic giant, reaching 6,263 meters (20,548 feet) above sea level. Due to its location near the equatorial bulge, Chimborazo’s summit is the farthest point from the Earth’s center, surpassing even Mount Everest. These immense structures demonstrate the varied geological processes, from subduction zones to mantle plumes, that create the planet’s largest volcanic formations.